One of the elements of eugenics is that the birth weight of newborns should reach normal standards. The current normal value of birth weight for newborns should be 2500 grams to 4000 grams, with female newborns being 110 grams lower than males. Newborns below 2,500 grams have higher morbidity and mortality rates, and poorer behavior and responsiveness than normal-weight children. The main factors that contribute to low birth weight are: age at first birth, week of pregnancy, number of pregnancies and multiple births, maternal health, maternal preferences, fetal sex and nutritional status. To make your baby’s birth weight standard, you should try to overcome bad habits. For example, we found some low weight babies because pregnant women are afraid of losing their former slim figure and lose weight, especially abstaining from meat, resulting in poor fetal development; some are worried that the fetus will be too big to leave stretch marks on the skin of the abdomen; others are afraid of being uncomfortable after eating, nausea, vomiting and other phenomena, and do not eat or drink, resulting in pregnancy anemia. This not only leads to palpitations and dizziness, but also causes chronic hypoxia in the fetus, which affects the growth and development of fetal brain cells and nerve cells. If the fetus is born with low weight, it will not only have poor physical strength, but also poor intelligence and slow reaction. Therefore, women during pregnancy should think more about the fetus, otherwise it will cause irreversible consequences. On the contrary, when more and more women are excited about giving birth to a super “big fat kid”, the situation is more worrying, in recent years, the average weight of newborn babies has been increasing year by year, newborn babies weighing 4000-4500 grams account for more than 10%. Overweight is detrimental to infant growth and development, and is a cause of diabetes, morbid obesity and cardiovascular disease later in life. The increase in the average weight of newborn infants also causes a parallel increase in the number of maternal cesarean deliveries, so it is important to avoid excessive nutritional intake during pregnancy. There is no optimal standard for infant birth weight, but according to experts’ long-term clinical practice, it is more scientific to control the birth weight of infants in China at around 3300 grams. In Japan, the birth weight of infants is generally controlled at about 3000 grams, and in Western countries such as Europe and the United States, the weight of infants is generally controlled at about 3400 grams. Such weight is very beneficial to reduce the rate of maternal cesarean section, maternal balanced nutrition, maternal postpartum body recovery and healthy growth of the baby.